However! I have solved a future iteration of this problem with our latest addition to the zoo. Meet Sam:
Sam is a hatchling Sulcata tortoise, and he is darling. Actually, "he" could very well be a "she" because it's difficult to sex tortoises accurately at this young an age, but for now we're just going to default to the masculine pronoun... in part because almost every other critter in my house is male so why should my luck change now? That said, if Sam becomes Samantha, my Bewitched-obsessed self will not be overly distressed.
In spite of his current petite flower status, Sam will eventually grow to be over 100 lbs., with a shell length of up to 32 inches. For now, though, he's completely dwarfed by his salad:
So much cuteness, I die!
Regarding how this fixes the pet death situation? Well in this case, barring any health issues, Sam should outlive both Brent and me. He has a life expectancy of over 70 years -- some sources say over 100 years -- so I think it's safe to say he's going to outlive us both. We'll have to make provisions for him in our will; the Gum Zombie has volunteered to take him on once we're gone. That said, the child is twelve so if things change we'll make alternate arrangements for this little fellow.
Who won't be very little at all by that point.
It's nice to have one pet I probably won't have to say goodbye to :)